1. Field of the Invention
This invention relates to a level monitoring and control system for agricultural implements and more particularly to a system with which a depth level is continuously monitored and with which a desired depth setting may be readily registered and re-established. The system is very reliable and accurate, is economically manufacturable and can be readily applied to existing implements or incorporated in implements during manufacture thereof.
2. Description of the Prior Art
In agricultural implements such as plows, harrows and the like, the plow bottoms, disks or other working elements must be controllably movable upwardly or downwardly during operation to adjust for varying soil conditions must be movable to a fully raised position for travel or to clear an obstacle. Hydraulic systems are generally used and in a typical system, a manually operable valve controls flow of a fluid to and from a hydraulic cylinder which operates a rockshaft arranged to control the vertical position of disks or plow bottoms. The hydraulic cylinder may be double-acting or may be single-acting with the force of gravity being relied upon to effect downward movement of the working element.
With such systems, the operator must exercise a great deal of care during operation to insure that the working element is at the proper level, and when the element is raised to clear an obstacle or hazard or to make a turn at the end of a row, the operator must readjust the level after clearing the hazard or completing the turn. Such readjustments are frequent and easily result in operator fatigue and inefficient operation.
Systems have been proposed which rely on mechanical stops. These systems cannot be adjusted during operation. The operator must dismount, predict some incremental change in depth, then make a mechanical change sometimes requiring tools.
Systems have also been proposed using in place of a manually operated valve an electrically operated valve controlled from a command potentiometer which is manually operated by the operator. Such systems might be more easily controlled with greater flexibility but those proposed have been relatively expensive and have other disadvantages including high power consumption in driving the pump of the hydraulic system.